I've worked both as a caddy and as a burgerflipper (figuratively, not literally). First, I'd say they're equally hard work physically. A single loop on a nice day is easier. Kitchen work is quite demanding.
I was at a prominent but not extravagant club in a mid-major city. It was very much top tier (the only reason there were caddies in the first place). The pay was basically $50 (2012 dollars) for a single, which was 5 hours work (all in time at the course). Most of the loops were singles, which can be fun. I'd always take a double for the money, but it was terrible. So, the money is not great but slightly better than kitchen work. But, it's less stable and predictable. And it's early, and it can be very hot. But, I love golf and caddying, so overall caddying might be better. But the problem was caddying for a hack who's being mildly condescending, just isn't that fun, so even though on paper flipping burgers might be worse, it can be preferable. The player was the factor that made caddying worthwhile or not, but that's a big unknown. If there's any real risk of not getting out after showing up, forget it.
I personally just worked a lot in the bag room, and took the good loops I could get. That included nice guys for average money and the big events where the money was better.
My experience was common. The only people that were really caddying a lot were doing it with the carrot of a scholarship or course access which changes the economics above. And because I played golf, caddied, and worked in the bag room, I actually had a better situation. A starting caddy (particularly one who didn't know the game), would have to spend more time paying his dues with worse loops and worse pay just to get to where it might make sense. But who would put in that time who didn't love the game? And country clubs aren't known to be easy to access without a car, so that makes all these numbers even worse.
I don't think you could go below $40 bucks for any sort of caddy/bag carrier in this country (and I think $50 is more reasonable). But even at that rate they person has options, and I don't think many would choose caddying vs other options. And as the cost starts to make sense for the caddy, it gets to be too much for the player.